DFT and Green’s Function Formalism Investigation of 2D Penta-NiN ₂ Nanosheets: Implications for Catechol Sensing

Inspired by the recent successful synthesis of the penta-NiN2 monolayer (ACS Nano, 2021, 15, 13539), we explore its potential as a highly sensitive and reusable sensor for the detection of the catechol (CC) biomolecule using the first-principles density functional theory (DFT) combined with Green’s function formalism. Our comprehensive study reveals that CC adsorption significantly modulates the electronic properties of the penta-NiN2 surface. In the presence of water, the adsorption energy increases from −0.85 eV (vacuum) to −0.89 eV (aqueous), indicating a stronger interaction. Projected density of states (PDOS) and Bader charge analysis show ∼0.03e charge transfer from CC to the NiN2 nanosheet. Notably, the adsorption of CC leads to a ∼1.7-fold increase in current through the NiN2 nanosheet channel, highlighting its potential in sensing applications. Reduced density gradient (RDG) analysis offers further insight into the noncovalent interactions governing the adsorption process. Ab-initio molecular dynamics (AIMD) simulations confirm the thermal stability of the system at 300 K. Moreover, the calculated recovery times under visible light are 0.28 s in dry and 1.28 s in aqueous environment, demonstrating excellent sensor reusability. These results position the penta-NiN2 nanosheet as a promising candidate for a real-time, reusable CC biosensing platform with high sensitivity, stability, and rapid response.